Dehider with governor and strengthened blade

ABSTRACT

A dehider includes a pneumatic motor driving a pair of disk blades in opposed cutting oscillations and a governor that controls the speed of the motor. Governor balls, acting as centrifugal weights, spin with the motor and push against an inclined flange on a valve head to move the valve head towards a valve seat. The motion of the valve head compresses a biasing spring and restricts the flow of pressurized air as the desired speed is exceeded. As speed decreases, centrifugal force decreases and the biasing spring opens the valve to provide additional power to the motor. The disk blades are provided with a cylindrical central lip that substantially increases the area of the central bearing that the blades turn on and produces significantly longer blade life.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to handheld dehiders and powered skinningknives used to remove the hide of a carcass in a meat processingfacility. More specifically, the present invention relates to dehidersthat use a pair of cutting disks driven in opposed cutting oscillations.

2. Description of Related Art

Handheld dehiders are used in meat processing facilities to remove thehide from an animal carcass. The most common type of dehider includes apair of adjacent cutting disks or blades that are driven in opposedcutting oscillations by a corresponding pair of pushrods. The basicdesign is shown in U.S. Pat. No. 5,122,092 assigned to Jarvis ProductsCorporation, the assignee of the present invention. Similar dehiderdesigns are shown and described in U.S. Pat. Nos. 4,368,560, 3,435,522and 2,751,680.

In the dehider design described in the patents above, each cutting bladeincludes teeth around its perimeter. The adjacent disk blades are drivenin opposed cutting oscillations by a pair of pushrods connected to aneccentric drive mechanism operated by a pneumatic motor mounted in thehandle of the tool.

The motor rotates a pinion gear, which turns a main drive gear orientedat ninety degrees to the axis of the motor. The main drive gear turnsthe eccentric shaft to oscillate the pushrods. During each oscillation,the teeth on one disk blade move past the teeth on the adjacent andoppositely moving disk blade. This produces a shearing and cuttingaction that quickly removes the hide from the carcass.

Although this dehider design has proven effective, existing designs tendto slow down under a heavy cutting load and then return to a higherspeed as the cutting load is removed. To achieve the optimum cuttingspeed while operating under load, dehiders of this type must be set torun at a higher speed when they are not cutting. This higher no-loadspeed produces undesirable increases in tool wear and noise. The excessspeed under the no-load condition is particularly problematical for adehider having oscillating blades due to the frequent forward and backreversals of the blades and pushrods and the wear associated with theoscillating motion at high speed.

Another problem in existing designs lies in the design of theoscillating disk blades. These blades have heretofore been constructedwith a constant thickness at all locations—except at the cutting edgeswhere the thickness decreases to form the sharpened blade edges andteeth. In particular, the inner bearing area of the cutting disk hasbeen of the same thickness as the outer portions of the blade. Eachblade rotates about a bearing formed by a hole in this inner bearingarea.

The limited thickness of the blade is advantageous at the outer edges ofthe blade, but it limits the bearing surface area at the center. Thelimited size of the bearing center hole produces wear at a greater ratethan is desirable. As the blade wears, the center hole enlarges untilthe blade eventually becomes unusable. Often, it is this center bearingwear that limits the useful life of the blade. If not for this excessbearing wear, the blade could be sharpened additionally and the usefullife of the blade extended.

Still another problem lies in the oscillating nature of theeccentric-driven pushrods and blades, which produces substantialvibration. A known method of reducing this vibration is to use acounterbalance mass on the main drive gear, however, this solution isonly partly effective. In order to avoid interference with theoscillating pushrods, the main drive gear and any counterbalance massconnected thereto must be vertically offset from the plane of thepushrods. The offset between the moving mass of the pushrods and theoppositely moving mass of the counterbalance on the main drive gearproduces a wobbling motion.

Initially, the magnitude of this wobbling motion is quite limited andthe tool can be used comfortably for long periods of time. However, overtime, the wobbling motion produces significant excess wear. As thebearings and moving parts begin to wear, the wobble increases inamplitude until it produces an extremely objectionable vibration.Moreover, the wear produced by this motion shortens the lifetime of thecomponent parts in the tool.

Bearing in mind the problems and deficiencies of the prior art, it istherefore an object of the present invention to provide a handhelddehider that operates at a nearly constant speed when operating under aload and when operating without a load.

Yet another object of the present invention is to provide a handhelddehider with blades that wear at the center bearing more slowly thanexisting designs.

A further object of the present invention is to provide a handhelddehider with less vibration that can be comfortably used for longperiods of time.

It is another object of the present invention to provide a handhelddehider that wears less rapidly due to reduced vibration.

Still another object of the invention is to provide a counterbalancedeccentric shaft for a handheld dehider with an integrated counterbalancemass.

It is yet another object of the present invention to provide acounterbalance cup for a handheld dehider with an integratedcounterbalance mass.

Still other objects and advantages of the invention will in part beobvious and will in part be apparent from the specification.

SUMMARY OF THE INVENTION

The above and other objects, which will be apparent to those skilled inthe art, are achieved in the present invention which is directed to ahandheld dehider having a pair of cutting disks mounted on a cuttingdisk shaft, and a drive mechanism for driving the cutting disks inopposed cutting oscillations. The drive mechanism includes an eccentricshaft and a pair of pushrods, one for each cutting disk, each pushrodbeing connected between the eccentric shaft and its respective cuttingdisk. A pneumatic motor mounted in a housing is connected to turn theeccentric shaft and oscillate the pair of pushrods. The housing includesan air inlet for providing a flow of pressurized air to the motor, and aspeed governor connected between the air inlet and the motor, the speedgovernor automatically controlling the flow of pressurized air from theair inlet to the pneumatic motor to maintain a desired rotational speedfor the motor.

In one aspect of the invention, the speed governor is connected to spinwith the pneumatic motor and operates by centrifugal force to restrictthe flow of pressurized air from the air inlet to the pneumatic motor todecrease the speed of the motor when the motor speed is above thedesired rotational speed.

In the preferred embodiment, the speed governor includes a valve headconnected to spin with the pneumatic motor and the air inlet isconnected to a valve seat. The valve head moves towards the valve seatto restrict the flow of pressurized air from the air inlet to thepneumatic motor and decrease the speed of the motor when the motor speedis above the desired rotational speed.

In another aspect of the invention, the speed governor includes agovernor spring biasing the valve head away from the valve seat and amovable mass connected to spin with the pneumatic motor. The movablemass moves outward as the speed governor spins and compresses thegovernor spring to move the valve head towards the valve seat andrestrict the flow of pressurized air from the air inlet to the pneumaticmotor.

The movable mass is preferably one or more governor balls that contactan angled flange on the valve head. As the balls spin, they exertcentrifugal force against the angled flange to compress the governorspring and move the valve head towards the valve seat.

In another aspect of the dehider design, the housing includes a drivemechanism cover having three pieces. A drive mechanism cover portion islocated over the drive gear. A barrier plate portion is located underthe pushrods and wall portion connects the drive mechanism cover portionto the barrier plate portion. The drive mechanism cover is preferably anintegral piece made of steel.

In still another preferred aspect of the dehider design, each cuttingdisk includes a central opening and a bearing lip surrounding thecentral opening. The central openings and bearing lips of the pair ofcutting disks form a bearing having an enlarged bearing surface thatsurrounds the cutting disk shaft. The cutting disk shaft may include acylindrical collar having an outer bearing surface that the centralopening and bearing lip of each cutting disk surrounds. The centralopenings and bearing lips of the pair of cutting disks cooperate to forma bearing having an inner bearing surface that contacts the outerbearing surface of the cylindrical collar.

In yet another aspect of the handheld dehider design, the dehiderhousing includes a first cover adjacent a first one of the pair ofcutting disks and a second cover adjacent a second one of the pair ofcutting disks. The first cover has a recess for receiving the bearinglip of the first one of the pair of cutting disks and the second coverhas another recess for receiving the bearing lip of the second one ofthe pair of cutting disks. The cylindrical collar may also be receivedin the recesses of the first and second covers.

The bearing lip surrounding the central opening of each cutting diskpreferably projects outwardly from only one side of each cutting disk sothat the pair of disks may be assembled back to back withoutinterference between their respective bearing lips.

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the invention believed to be novel and the elementscharacteristic of the invention are set forth with particularity in theappended claims. The figures are for illustration purposes only and arenot drawn to scale. The invention itself, however, both as toorganization and method of operation, may best be understood byreference to the detailed description which follows taken in conjunctionwith the accompanying drawings in which:

FIG. 1 is a top plan view of a first embodiment of a dehider accordingto the present invention.

FIG. 2 is a right side elevational view of the first embodiment of thedehider of the present invention, taken in cross section along the line2-2 in FIG. 1.

FIG. 3 is a perspective view of an eccentric with an integrated firstcounterbalance according to the present invention as seen in FIGS. 1 and2.

FIG. 4 is a top plan view of a second counterbalance according to thepresent invention as seen in FIGS. 1 and 2.

FIG. 5 is a bottom plan view of the second counterbalance seen in FIG.4.

FIG. 6 is a side elevational view of the second counterbalance seen inFIG. 4.

FIG. 7 is a side elevational view, in cross section, of a portion of asecond embodiment of a dehider according to the present invention. Onlythe central portion of the dehider is shown in the vicinity of the drivemechanism and eccentric.

FIG. 8 is a side elevational view of an assembled drive mechanism of athird embodiment of a dehider according to the present invention.

FIG. 9 is a side elevational view, in cross section, of the speedgovernor portion of the present invention as seen in FIGS. 1 and 2.

FIG. 10 is a side elevational view, in cross section, of the blade hubportion of the present invention as seen in FIGS. 1 and 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

In describing the preferred embodiment of the present invention,reference will be made herein to FIGS. 1-10 of the drawings in whichlike numerals refer to like features of the invention.

FIGS. 1 and 2 show a handheld dehider 10 according to a first embodimentof the present invention. The dehider 10 includes a pair of adjacentcutting disks 12 and 14 having teeth 16 located around the perimeter ofeach disk. The cutting disks 12, 14 are driven by a pair of pushrods 18,20 in opposed cutting oscillations by an eccentric shaft 22 (seen bestin FIG. 3).

The eccentric shaft 22 is driven by pneumatic motor 24 located in thehandle 26 of the tool housing. The motor 24 drives pinion gear 28, whichengages and turns the main drive gear 30. The main drive gear 30 ismounted on the eccentric shaft 22 such that rotation of the motor andpinion gear turns the main drive gear and eccentric shaft to drive thepushrods and cutting disks.

The eccentric shaft 22 is held between a pair of bearings 32, 34 mountedin the housing 36 of the dehider. The housing includes the handle 26 atthe back of the tool and a forward end of the tool that wraps around andbelow the drive area and extends underneath the cutting disks. Thehousing also includes a drive mechanism cover 37 that extends over thedrive area and immediately below the cutting disks, and a blade cover 39located above the cutting disks. The housing design allows easy cleaningand removal of the drive mechanism without removing the motor.

The drive mechanism cover 37 includes three pieces including a drivemechanism cover portion 41, a barrier plate portion 45 and wall portion43 that connects the other two pieces. The drive mechanism cover portion41 covers the top of the gear assembly and provides access thereto. Thebarrier plate 45 passes underneath the cutting disks and separates themfrom the pushrods. The wall portion 43 connects the other two pieces andfurther isolates the drive mechanism from the cutting disks.

These three pieces cooperate to substantially seal the drive mechanisminside the tool and separate the drive mechanism and pushrods from thecutting disks 12, 14. The cutting disks 12, 14 are located on one sideof the barrier plate, in contact with the flat portion thereof. Thebarrier plate 45 serves not only as a barrier against the entry ofcontaminating material, but also as a flat bearing surface against whichthe cutting disk 14 slides. This large flat bearing surface stabilizesthe cutting disks and prevents them from twisting during use.Accordingly, to minimize wear, the barrier plate is preferably made of aharder material than the remainder of the housing. Prior art designswhich incorporated the barrier plate into the housing were required tomake the housing and the barrier plate of the same material. As aresult, additional processing steps were required to properly harden theface of the barrier plate and prevent undue wear.

In the present invention, both the drive mechanism cover portion and thebarrier portion are preferably made of steel. Moreover, the steel formsan excellent material for receiving the bearing 32, and in the eventbearing 32 locks up, the damage caused will be less than if the drivemechanism cover were manufactured of aluminum. If the damage isexcessive, the drive mechanism cover may easily be replaced.

The main drive gear 30 has inwardly facing teeth and is driven by themotor 24 through the pinion gear 28. Because the main drive gear ismounted on the same side of the pinion gear as the drive mechanismcover, the complete drive mechanism may be removed from the housingmerely by removing the drive mechanism cover.

The pushrods 18, 20 are driven by the eccentric shaft such that the backends of the pushrods are concentrically engaged by the eccentric andmove in a circle as the eccentric shaft turns. The front ends of thepushrods move forwards and backwards approximately parallel to the axisof the dehider tool. The moving front ends are connected to the cuttingdisks 12, 14, through the barrier plate, with one pushrod to each disk.

Each pushrod extends to an opposite side of the cutting disk shaft 38and connects to its associated cutting disk on its respective side ofthe cutting disk shaft. As each pushrod moves forward, it turns thecutting disk it is connected to in the opposite direction from thecutting disk being driven by the other pushrod on the opposite side ofthe cutting disk shaft 38. This produces the opposed cutting diskoscillations of this tool.

During each cutting oscillation the teeth 16 on cutting disk 12 pass bythe oppositely moving teeth on adjacent cutting disk 14. As theeccentric shaft continues to rotate, the pushrods 18, 20 are drawn backand the direction of motion of the cutting disks 12, 14 is reversed.This causes the cutting teeth 16 on one cutting disk to again pass bythe oppositely moving teeth on the other cutting disk to produce ascissors-like action between the oppositely moving teeth that quicklyand effectively allows the dehider operator to remove the hide of thecarcass.

A more detailed description of operation and the advantages of thehousing design can be found in U.S. Pat. No. 5,122,092, assigned toJarvis Products Corporation, the assignee of the present invention, thedisclosure of which is incorporated herein by reference.

From the description above, it will be understood that all hand-helddehiders of this basic design are subject to a vibration resulting fromthe oscillating mass of the pushrods and cutting disks being driven bythe eccentric drive system. During each rotation of the eccentric shaft,the two pushrods are driven forward and back, and the disk blades areaccelerated in a first direction, then stopped and accelerated in theopposite direction.

A known method of reducing this vibration is to provide a counterbalancemass on the main drive gear 30. The counterbalance mass on the maindrive gear (which is located in the drive section near the top of thetool in FIG. 2) is arranged so that it is moving back (towards thehandle of the tool) as the eccentric portion of the eccentric shaft(located in the drive section near the bottom of the tool in FIG. 2) ismoving the two pushrods forward (towards the cutting disks on theworking end of the tool).

The principal difficulty with this method of vibration reduction residesin the fact that it does not provide true dynamic counterbalancing forthe dehider. To provide clearance for the pushrods, and to allow thedrive mechanism to be removed without removing the motor, the main drivegear must be located above the axis of the motor—in a plane that is wellabove the plane of the oscillating mass of the pushrods. Consequently,as the pushrods are being driven forward by the eccentric, there is abackwards reaction force that is applied low in the drive section of thetool (where the eccentric and pushrods are located). Simultaneously, thecounterbalance mass on the main drive gear is moving backwards, but thisproduces a forward reaction force that is applied high in the drivesection of the tool, where the main drive gear must be located.

Although the forces produced by the counterbalance and the moving massesare in the opposite direction, because they are not aligned in the sameplane, they do not cancel completely. The force low in the tool's drivesection from the moving masses and the force high in the drive sectionproduce a reinforcing torque on the tool that reverses direction witheach oscillation of the cutting disks. The result is that in prior arttools, even tools with drive gear counterbalancing, the tool is notdynamically counterbalanced and a wobbling motion is imparted thatproduces significant wear on the tool's drive components.

Initially the wobbling motion is relatively small, but as the bearingsand pushrods begin to wear, the level of vibration and the wobblingmotion increases rapidly to objectionable levels. The present inventionaddresses this problem by providing two counterbalance masses located onopposite sides of the plane of the pushrods. The two counterbalancemasses cooperate to provide counterbalancing which acts at a locationbetween the counterbalance masses and directly opposite and in the sameplane as the oscillating mass of the pushrods.

In the preferred embodiment of this invention, the counterbalance massabove the plane of the pushrods is removed from the main drive gear andis shifted onto a separate counterbalance cup 54 (see FIGS. 4-6) thatalso acts as a spacer. By removing the counterbalance mass from the maindrive gear, it can be moved closer to the plane of the pushrods, whichreduces the torque produced and the resulting wobbling motion. Inaddition, the cost of manufacturing the complex main drive gear issubstantially reduced.

FIG. 3 shows an eccentric shaft according to the present invention usedin the preferred dehider design of FIGS. 1 and 2. The eccentric shaft 22includes first and second cylindrical shaft sections 42, 44 which fitinto bearings 34 and 32, respectively. The eccentric shaft portion 46 iscentrally located and cylindrical bearings on the rear ends of thepushrods fit onto the eccentric shaft portion 46. Adjacent to theeccentric shaft portion 46 is a first counterbalance mass 48. It will benoted that the first counterbalance mass 48 is substantially on theopposite side of the shaft 22 from the eccentric portion 46. Thus, whenthe pushrods are moving toward the front of the tool in FIGS. 1 and 2,the counterbalance mass 48 will be moving toward the back of the tool.

It will also be seen that the counterbalance mass 48 is extremely closeto the eccentric shaft section 46. Accordingly, even without the secondcounterbalance mass on the counterbalance cup 54, the location of thefirst counterbalance mass 48 close to the plane of the pushrods improvescounterbalancing as compared to the offset location of the prior art onthe main drive gear.

The main gear 30 is mounted on the eccentric shaft 22 on a gear shaftportion 50 adjacent to the bearing shaft portion 44.

In order to provide true dynamic counterbalancing, the counterbalancingmass should be located directly opposite the eccentric approximately inthe plane of the pushrods 18, 20. However, this location would produceinterference between the counterbalance mass and the pushrods as thepushrods move to the rear of the tool and the counterbalance mass mustmove to the front of the tool. Accordingly, a second counterbalance mass52 is located on the opposite side of the eccentric and the pushrodsfrom the first counterbalance mass 48 such that the effectivecounterbalancing mass acts at a point between the first and secondcounterbalancing masses.

In the preferred design, the second counterbalancing mass is integratedinto the counterbalance cup 54 seen in FIGS. 4, 5 and 6. Thecounterbalance cup 54 includes a shaft opening 56 that extendscompletely through the counterbalance cup and defines an axis ofrotation 58 for the counterbalance cup. The second counterbalance mass52 is offset to one side of the axis of rotation 58 and a cup opening 60that extends only partially through the counterbalance cup has a center62 (see FIG. 6) that is offset in the opposite direction from thecounterbalance mass 52.

As may be seen by comparing FIGS. 3 and 6 to the cross sectional view inFIG. 2, the counterbalance cup 54 slides onto the eccentric shaft 22.Shaft opening 56 matches the diameter of the eccentric shaft in theregion 64 while the cup opening 60 is sized to receive and engage theeccentric portion of the shaft 46 in the region marked with referencenumber 66. Because the center 62 of the cup opening 60 is offset fromaxis 58, the engagement between the cup opening 60 and the eccentricshaft portion 46 acts to prevent the counterbalance mass 52 fromrotating relative to the eccentric shaft 22. The second counterbalancemass 52 always remains on the same side of the shaft 22 as the firstcounterbalance mass 48, and that side is always opposite the side of theshaft from the eccentric 46.

This dual counterbalance design produces an effective dynamiccounterbalancing that acts substantially opposite to the masses beingdriven by the eccentric motion and eliminates the wobbling motiondescribed above. The result is to significantly reduce wear, extend thelife of the drive components and increase the time the tool can be usedwithout operator fatigue.

It should be noted that the present invention is directed not only tothe dual counterbalance dehider design of FIGS. 1 and 2, but also to theindividual drive components for a hand held dehider comprising theeccentric shaft of FIG. 3 with the integrated counterbalance 48 and thecounterbalance cup seen in FIGS. 4, 5 and 6 with the integratedcounterbalance mass 52.

The design illustrated in FIGS. 1-6 allows the counterbalancing masses48 and 52 to be extremely close to the plane of the pushrods and themoving masses. As a result any remaining imbalance or imbalance fromsubsequent wear or manufacturing variation results in a very reducedamplitude wobble as compared to prior art counterbalancing designs witha single counterbalance located far from the plane of the pushrods.

Although the preferred embodiment is seen in FIGS. 1 and 2, analternative embodiment is seen in FIG. 7 in which one counterbalanceremains on the main drive gear, as in the prior art, and a secondcounterbalance is located on the opposite side of the pushrods on theeccentric shaft. In FIG. 7, only a detailed portion of the drivemechanism is shown. The portion shown substantially corresponds to thecentral area showing the eccentric shaft 22 in the cross sectional viewof FIG. 2.

However, in the design of FIG. 7, the counterbalance cup of FIGS. 4, 5and 6 is replaced by the prior art counterbalanced main drive gear 70with an integrated counterbalance mass 72. As can be seen in theenlarged view of FIG. 7, the counterbalance mass 72 is located on oneside of the main drive gear 70. The counterbalance cup of FIGS. 4, 5,and 6, which is used in the design of FIGS. 1 and 2, is replaced by asimple spacer cup 74 located between the main drive gear 70 and theeccentric 46. The spacer cup has no counterbalance mass.

In all other respects the embodiment in FIG. 7 corresponds to theembodiment in FIG. 1-6. Counterbalance mass 48 on the eccentric shaft islocated on the opposite side of the pushrods from the counterbalancemass 72 on the drive gear. As in the design in FIGS. 1-6, these twocounterbalance masses cooperate to provide dynamic counterbalancing thatacts substantially opposite the eccentric 46 in the plane of thepushrod.

FIG. 8 shows yet another embodiment of the counterbalanced drivemechanism of this invention. In this design, both of the counterbalancemasses are entirely separate from the eccentric shaft. The firstcounterbalance mass 80 is a separate piece located below the eccentricshaft portion 46 where the pushrods are connected (shown in phantom 82).The first counterbalance mass 80 in this design is held in place by apin 84 to prevent it from rotating around the eccentric shaft. The pin84 ensures that the first counterbalance mass 80 always remains oppositethe offset direction of the eccentric shaft portion 46.

The first counterbalance mass 80 is removable and replaceable bydisassembling the drive mechanism of FIG. 8, removing pin 84 and slidingthe first counterbalance mass 80 off the end of the eccentric shaft.

The second counterbalance mass 72 is located on the main drive gear, asin the design of FIG. 7, above the eccentric shaft portion 46. Thesecond counterbalance mass 72 is on the opposite side of the rotationalaxis of the eccentric shaft from the offset eccentric shaft portion 46and on the same side of that axis as the first counterbalance mass 80.

It will be understood from the various embodiments shown that the firstand second counterbalance masses may be formed as part of the eccentricshaft (FIG. 3), as part of the drive gear (FIGS. 7 and 8), or asseparate pieces, such as the counterbalance cup (FIGS. 4-6) or the firstcounterbalance mass 80 (FIG. 8). In each case, one counterbalance massis located above the plane of the pushrods, and one below that plane sothat the vibration due to the eccentrically driven moving mass of thetool is effectively and dynamically counterbalanced.

In addition to the dual counterbalance feature described above, thepreferred embodiment of the dehider also includes a speed governor 100located in the handle 26. The speed governor operates by restricting theflow of pressurized air from the air inlet 102 to the motor 24 when themotor is rotating rapidly and opening up to supply more pressurized airwhen the motor slows down.

Referring to FIG. 9, the design and operation of the speed governor 100will now be described. Pressurized air from the air inlet 102 flows intoair passageway 104. The air passageway 104 includes a valve seat 106.Opposite the valve seat 106 is a valve head 108 that can move towardsthe valve seat 106. The valve head 108 has a beveled end 110 that actsto restrict airflow through the space between the valve seat 106 and thebeveled end 110. Air that passes through the space between the valveseat 106 and the beveled end 110 eventually powers the motor 24.

The valve head 108 is biased to the right, as illustrated in FIG. 9 bygovernor spring 112. The governor spring 112 surrounds the core 116 andis trapped between an outwardly projecting lip 114 on the core 116 andan inwardly projecting lip 118 on the valve head 108.

The valve head 108 also includes an outwardly angled flange 120 thattraps a plurality of governor balls 122 between the angled flange 120,the core 116 and a governor housing 124. The valve head 108, core 116,governor housing 124, governor balls 122 and the governor spring 112 allspin with the motor 24. As the governor balls 122 spin with the motor,centrifugal force attempts to drive them outward and up the angledflange 120 between the angled flange 120 and the governor housing 124.

The governor balls 122 act as a movable mass that operates the governorby centrifugal force. The outward motion of the governor balls applies aforce against the angled flange 120 and the valve head 108, whichcompresses the spring 112 and moves the beveled end 110 of the valvehead 108 towards the valve seat 106. The faster the motor spins, themore this valve action restricts the airflow and the less pneumaticpower is supplied to the motor.

As the dehider begins to cut and the load on the motor increases, thespeed of the motor will drop. This decrease in speed will cause thecentrifugal force applied by the governor balls to the valve head 108 todecrease. In turn, the spring 112 will move the valve head 108 away fromthe valve seat and the valve will open further, allowing more airflow.The result of increased airflow is that the motor will produce morepower and will return to the original operating speed even under load.

The governor 100 will control the speed in the manner described undersignificant variations in operating load. When the motor is above thedesired rotational speed, the governor restricts the flow of pressurizedair to decrease speed. When the motor is below the desired rotationalspeed, the governor opens up to increase airflow and increase themotor's speed.

The preferred embodiment of the dehider further includes an improvedcutting disk design for the cutting disk blades 12 and 14. The cuttingdisks 12 and 14 turn on central cutting disk shaft 38, which includes anupper bolt 150, a lower nut 152 and a cylindrical collar 154. The collar154 has an outer surface 156 that acts as the bearing surface thecutting disks 12 and 14 turn on. In current dehider designs, the diskblades are of a constant thickness. However, as can be seen in FIG. 10,the strengthened cutting disks 12, 14 of this dehider have a cylindricallip (158 on cutting disk 12 and 160 on cutting disk 14) thatsignificantly increases the bearing surface between the cutting disksand the outer bearing surface 156 of the collar 154.

In the preferred design, the cutting disks are produced from materialthat is thicker than the final thickness of the outer area of the disk,and equal in thickness to the cylindrical bearing lips 158 and 160 atthe center of the disk. The disk blades are ground to reduce theirthickness everywhere except at the cylindrical bearing lips 158 and 160.Alternatively, however, the bearing lip may be added by a process suchas by brazing or welding on additional material, or by deforming athinner sheet at the inner perimeter to form the lip.

The reduction in thickness of the disk blade in the outer area ascompared to the thickness of the cylindrical lip at the center of thedisk blade has two principal advantages. The first is that the weight ofeach cutting disk blade is reduced. This reduces the oscillating mass,which reduces wear and vibration, as well as reducing the total weightof the dehider. The second advantage is that the total thickness of thecombined cutting disks 12 and 14 is reduced, which allows the cuttingdisks to enter the space between the carcass and the hide more easilyfor hide removal and improves cutting performance as compared to thickercutting disks.

It will be noted that the cutting disks 12 and 14 are identical exceptthat one is inverted relative to the other The bearing lips 158, 160project outward at ninety degrees to the plane of their respectivecutting disks. When the cutting disks are inverted and placed inback-to-back contact with each other, as illustrated, the lips 158 and160 project in opposite directions and do not interfere with each other.The result is a substantial increase in the area of the bearing surfaceat the center of the tool and a substantial increase in the usable lifeof the cutting disks.

The upwardly projecting bearing lip 158 on cutting disk 12 is capturedinside a corresponding recess 162 in the blade cover 39. The downwardlyprojecting bearing lip 160 on cutting disk 14 is captured inside asimilar cylindrical recess 164 formed in the drive mechanism cover 37.The recesses 162 and 164 also provide clearance for the cylindricalcollar 154.

The outward projection of the bearing lips 158 and 160, in combinationwith the shape of the recesses 162 and 164 also act to preventcontaminants from entering the bearing area between the outer bearingsurface of the cylindrical collar 154 and the inner bearing surfaceformed by the bearing lips 158 and 160 and the central openings of thecutting disks.

Although the bearing lip design described above is most suited forhandheld dehiders having oppositely oscillating cutting disk blades, itmay also be implemented in dehider designs where a single cutting diskcontinuously rotates, where a pair of cutting disks continuously rotatein opposite directions or in dehider designs where a single bladeoscillates and another blade remains still.

While the present invention has been particularly described, inconjunction with a specific preferred embodiment, it is evident thatmany alternatives, modifications and variations will be apparent tothose skilled in the art in light of the foregoing description. It istherefore contemplated that the appended claims will embrace any suchalternatives, modifications and variations as falling within the truescope and spirit of the present invention.

1. A method of reducing wear and vibration of a handheld dehider bylimiting rotational speed comprising the steps of: providing a handhelddehider housing having an air inlet for providing a flow of pressurizedair; positioning a pneumatic motor within the housing and connected tothe air inlet, the motor defining a motor axis; mounting a pair ofcutting disks to the housing on a cutting disk shaft; connecting a drivemechanism between the cutting disks and the motor to drive the cuttingdisks in opposed cutting oscillations, the drive mechanism including: aneccentric shaft having an eccentric portion, a pair of pushrods, one foreach cutting disk, each pushrod being connected between the eccentricportion of the eccentric shaft and its respective cutting disk, and atleast one counterbalance mass positioned to at least partiallycounterbalance the moving pushrods and eccentric portion of theeccentric shaft; providing a speed governor having: a valve head axiallymovable towards and away from a valve seat, a governor spring biasingthe valve head away from the valve; and a movable mass, the movable massbeing radially movable towards and away from the motor axis; spinningthe movable mass of the speed governor with the pneumatic motor; movingthe movable mass outward under centrifugal force as the motor spins;compressing the governor spring as the movable mass moves outward undercentrifugal force; moving the valve head towards the valve seat as thegovernor spring is compressed; and restricting the flow of pressurizedair from the air inlet to the pneumatic motor as the valve head movestowards the valve seat to limit the speed of the motor and maintain adesired rotational speed to reduce wear and vibration of the handhelddehider.
 2. The method according to claim 1 wherein the speed governoris connected to spin with the pneumatic motor.
 3. The method accordingto claim 1 wherein the movable mass comprises a plurality of governorballs.
 4. The method according to claim 3 wherein the step of moving thevalve head towards the valve seat as the governor spring is compressedfurther includes providing an angled flange on the valve head, thegovernor balls contacting the angled flange and exerting centrifugalforce against the angled flange as the motor spins to compress thegovernor spring and move the valve head towards the valve seat.
 5. Themethod according to claim 1 wherein the housing further includes a drivemechanism cover, the drive mechanism cover including a drive mechanismcover portion, a barrier plate portion and wall portion connecting thedrive mechanism cover portion to the barrier plate portion.
 6. Themethod according to claim 1 wherein drive mechanism cover is made ofsteel.
 7. The method according to claim 1 wherein each cutting diskincludes a central opening and a bearing lip surrounding the centralopening, the central openings and bearing lips of the pair of cuttingdisks forming a bearing surrounding the cutting disk shaft.
 8. Themethod according to claim 1 wherein the step of connecting a drivemechanism between the cutting disks and the motor to drive the cuttingdisks in opposed cutting oscillations further includes providing asecond counterbalance mass on the eccentric shaft to furthercounterbalance the moving pushrods and eccentric portion of theeccentric shaft.
 9. The method according to claim 8 wherein the secondcounterbalance mass is positioned on the eccentric shaft to dynamicallycounterbalance the moving pushrods and eccentric portion of theeccentric shaft.
 10. A handheld dehider having reduced vibration bycounterbalancing and automatically limiting rotational speed, thehandheld dehider comprising: a pair of cutting disks mounted on acutting disk shaft; a drive mechanism for driving the cutting disks inopposed cutting oscillations including: an eccentric shaft, theeccentric shaft having a rotational axis and an eccentric portion havingan eccentric axis offset from the rotational axis; a pair of pushrods,one for each cutting disk, each pushrod having a back end connected tothe eccentric portion of the eccentric shaft and a front end connectedto a respective one of the cutting disks, the pushrods and eccentricportion of the eccentric shaft forming a moving mass offset from therotational axis of the eccentric shaft; and a counterbalance mass drivenwith the eccentric shaft and positioned to at least partiallycounterbalance the moving mass of the pushrods and eccentric portion ofthe eccentric shaft; a pneumatic motor connected to rotate on a motoraxis and turn the eccentric shaft and oscillate the pair of pushrods inopposed cutting oscillations; a housing having the pneumatic motormounted therein and including an air inlet for providing a flow ofpressurized air to the motor; and a speed governor connected to the airinlet of the housing to vary the flow of pressurized air from the airinlet to the pneumatic motor, the speed governor being connected to themotor to spin about the motor axis and automatically maintain a desiredrotational speed for the motor, the speed governor including: at leastone movable centrifugal mass located within the speed governor androtating about the motor axis; and a biasing spring biasing the speedgovernor to increase the flow of pressurized air from the air inlet tothe pneumatic motor; the centrifugal mass moving under appliedcentrifugal force away from the motor axis as the speed governorincreases speed to restrict the flow of pressurized air from the airinlet to the pneumatic motor and decrease the speed of the motor whenthe motor speed is above the desired rotational speed.
 11. The handhelddehider according to claim 10 wherein the speed governor is connected tospin with the pneumatic motor and operates by centrifugal force torestrict the flow of pressurized air from the air inlet to the pneumaticmotor to decrease the speed of the motor when the motor speed is abovethe desired rotational speed.
 12. The handheld dehider according toclaim 10 wherein the speed governor includes a valve head connected tospin with the pneumatic motor and the air inlet is connected to a valveseat, the valve head moving towards the valve seat to restrict the flowof pressurized air from the air inlet to the pneumatic motor anddecrease the speed of the motor when the motor speed is above thedesired rotational speed.
 13. The handheld dehider according to claim 12wherein the speed governor further includes: a governor spring biasingthe valve head away from the valve seat; and a movable mass connected tospin with the pneumatic motor, the movable mass moving outward as thespeed governor spins and compressing the governor spring to move thevalve head towards the valve seat and restrict the flow of pressurizedair from the air inlet to the pneumatic motor.
 14. The handheld dehideraccording to claim 13 wherein the movable mass comprises a plurality ofgovernor balls.
 15. The handheld dehider according to claim 14 whereinthe governor balls contact an angled flange on the valve head and exertcentrifugal force against the angled flange as the motor spins tocompress the governor spring and move the valve head towards the valveseat.
 16. The handheld dehider according to claim 10 wherein the housingincludes a drive mechanism cover, the drive mechanism cover including adrive mechanism cover portion, a barrier plate portion and wall portionconnecting the drive mechanism cover portion to the barrier plateportion.
 17. The handheld dehider according to claim 16 wherein drivemechanism cover is made of steel.
 18. The handheld dehider according toclaim 10 wherein each cutting disk includes a central opening and abearing lip surrounding the central opening, the central openings andbearing lips of the pair of cutting disks forming a bearing surroundingthe cutting disk shaft.
 19. The handheld dehider according to claim 10wherein: the cutting disk shaft includes a cylindrical collar having anouter bearing surface; and each cutting disk includes a central openingand a bearing lip surrounding the central opening, the central openingsand bearing lips of the pair of cutting disks forming a bearing havingan inner bearing surface, the central openings and bearing lips of thepair of cutting disks surrounding the cylindrical collar and the innerbearing surface contacting the outer bearing surface of the cylindricalcollar.